On Valentine’s Day, it’s tempting to check your wall every 10 min. to see if that cute guy from the bar last week has poked you. But a recent Psychological Science study by researchers at the University of Virginia and Harvard says you will probably like him more if he ignores you than if he posts flirty messages.

The study complicates decades of research on the “reciprocity principle,” which says that people fancy others who show fondness for them. As psychologists Erin Whitchurch, Timothy Wilson and Daniel Gilbert explain the principle, “If we want to know how much Sarah likes Bob, a good predictor is how much she thinks Bob likes her.” (More on TIME.com:5 Little-Known Truths About American Sex Lives)

But recent research on non-romantic attractions — how much consumers like a certain product, say — shows that there can be pleasure in uncertainty. If you discover that your lottery ticket is a winner, you feel happier when you don’t yet know the precise amount of your coming treasure than you do when you instantly learn its value. Or take Christmas: kids (and adults) often enjoy the anticipation of Santa’s visit more than the actual presents he brings.

As the authors write, “When people are certain that a positive event has occurred, they begin to adapt to it.” That adaptation makes it all less thrilling. By contrast, “when people are uncertain about an important outcome, they can hardly think about anything else.”

This expectancy can create a “self-perception effect,” a psychological phenomenon first described by the respected researcher Daryl Bem in the late ’60s. Bem noted that people often form attitudes about themselves by observing their own behaviors. In this case, the self-perception effect would roughly translate to “I must like him if I keep checking my wall to see if he pops up.”

To test whether the uncertainty theory applies to romantic attraction, Whitchurch, Wilson and Gilbert devised a simple experiment. They recruited 47 women from the University of Virginia and told them they would be participating in a study exploring whether Facebook is a useful dating site. The researchers also said several male students from the University of Michigan and UCLA had viewed their profiles — which was a lie. The male students were fictional. (More on TIME.com: Texting Leads to Sex Sooner–And Easier Break-Ups Later)

Each participant was told she would see the Facebook profiles of four of the guys. Then the participants were randomly split into three groups. In Group 1, each woman was told that the four guys had all said they expected to like her best. In Group 2, each woman was told she would see profiles of four men who had given her average ratings.

Finally, the women in Group 3 were told that their four men might be those who liked them most and might be those who thought they were average. This was the uncertainty group.

Then all the participants rated the men according to how much they liked them, how much they wanted to work with them on a class project, and — cutting to the chase — how much they wanted to hook up with them.

The results confirmed the reciprocity principle — the women in Group 2 had less desire for the guys whose profiles they saw than the women Group 1, who saw the profiles of the guys who thought they were hot. But the women in Group 3, the uncertainty group, were even more attracted to their men — men whose feelings they didn’t know. As the authors write, “Women were more attracted to men when there was only a 50% chance that the men liked them best than when there was a 100% chance that the men liked them the best.” (More on TIME.com: Will Facebook Steal Online Dating Sites’ Girl?)

In short, guys, you’re right to play hard to get. This Valentine’s, you can spark her attention by not poking her.